The world must prepare for a “climate endgame” to better understand and plan for the potentially catastrophic impacts of global warming that governments have yet to account for, scientists warned on Tuesday.
Climate models that can predict the magnitude of global warming based on greenhouse gas emissions are increasingly sophisticated and provide decision makers with an accurate trajectory of global temperature increase.
What is less well explored is the cascading impact of certain events, such as crop failures and loss of infrastructure due to extreme weather events, which are more likely to occur with each degree of warming.
Researchers from the University of Cambridge and the Potsdam Institute for Climate Impact Research (PIK) described what is currently known about “catastrophic outcomes” and found gaping knowledge gaps.
Writing in the journal Proceedings of the National Academy of Sciences, they proposed an international research agenda to help governments plan for the “worst cases.”
These included four main areas of concern – what the authors called the “four horsemen” of climate change: famine and malnutrition, extreme weather, conflict and vector-borne diseases.
“The irreversible and potentially catastrophic risks caused by human-induced climate change must be factored into our planning and actions,” said Johan Rockstrom, PIK director and co-author of the study.
He said more research being done on tipping points in Earth’s climate – such as the irreversible melting of ice caps or the Amazon rainforest changing from a carbon sink to a source – has shown the ever-greater need. to take into account high-risk scenarios in the climate. modeling.
“The key is to calculate the disaster, in order to avoid it,” he said.
– ‘Mismatched caution’ –
The authors pointed out that successive UN climate science reports have primarily focused on the projected effects of a warming of 1.5-2°C and have largely discounted the possibility of more excessive temperature increases.
The government’s plans put the Earth on track to warm up to 2.7C this century, a far cry from the 1.5C cap envisioned in the 2015 Paris climate accord.
The study suggested that a scientific disposition to “err on the side of less drama” has led to a lack of focus on potential impacts at 3°C or more of warming.
“This warning is understandable, but it does not correspond to the potential risks and damages posed by climate change,” he said.
Additionally, risk assessments for so-called low-probability, high-impact events are notoriously difficult to incorporate into long-term climate modelling.
Researchers have calculated that extreme heat zones – with an average annual temperature of over 29C – could cover two billion people by 2070.
They warned that temperatures posed a greater risk of multiple ‘breadbasket failures’ due to drought like that in Western Europe and heat waves like the one that hit India’s wheat crop in March /april.
The team called for a special UN science report focusing on “catastrophic climate change scenarios” similar to its 2018 report on 1.5C warming.
“We must take seriously understanding the profound risks that come with our planet moving into uncharted territory,” said Joeri Rogelj, senior research fellow at Imperial College London’s Grantham Institute, who did not participated in the study.
“Finding these edge cases means we will be able to prepare better, including being more serious about reducing emissions now.”